Outside Air Temperature Discrepancy

[tannerk89]

The car uses battery temps to control the cooling loops for the battery, not the outside ambient air temp. So even if your ambient temp sensor isn’t calibrated correctly your batteries shouldn’t be affected too much. It may use ambient temp for pre-conditioning when plugged in, but if it turns on a bit early at 100* vs 110* actual ambient is that really such a bad thing? Although it’s unlikely ambient temp sensor is much of a factor at all in battery cooling.

Also, are you basing your cars temp being wrong off of a weather app on your phone? I would compare to a thermometer rather than a weather app if I thought it was off.

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[metalpro2021]

Real issue: temp is not updated if the car is parked. Period. And update interval algorithm SEEMS not accepting high leaps in temp changes, so it slowly updates to the right temp. This can take 10 minutes. Let's illustrate this with a use case: If the night is cold and you want to leave. Temps have increased heavily in the meantime and let's say it is in the 80-ies. You remote start the car, because you want to cool the cabin. This is not done correctly because the 'not update temp' is used as a benchmark. You drive the car, and the car still displays the colder temp. It is steadily updated to a more correct value over time and the AC starts cooling. Situation seen daily on job 1, 2.7.3 updated AWD ER.

 

[macchiaz-o]

I have a Job 1 car with the 21P22 software update. I understood the update was intended to reduce the excessive fan noise during charging. Did it also reduce my ability to idle the car (or to sit in traffic) with the AC running? I had not heard about that.

I'm in the same boat as you. I'm unaware of any reduction in the ability to idle the car in high heat. I am not worried about it.

I don't think we will ever know what changes Ford made to the software.

True. Even the software/firmware engineers who made the changes might not know all the impacts of their own changes. Systems integration and software engineering are both rather complex at modern day scale. We do the best we can within time/budget restrictions, though.

If driving in ambient temps over 113F and caught in a traffic jamb moving at a slow crawl then the car will start to over heat. When that happens, the A/C to the cabin is limited and starts to blow warm air.

What I've noticed is that if I park the car outside, like I do at work, and it heats up, then when I go to use the car, the AC vent flow is not as strong or as cold as it would be if I were starting from a garaged/cooler condition.

So for example let's say Friday and Saturday have the same weather but I parked outside in the morning on Friday. On both days, if I leave to go somewhere around 12pm, then it's gonna take a lot longer for the cabin to be comfortable on Friday (no shade) versus Saturday (garaged).

My GUESS based on my observations is that the HVAC is prioritizing battery pack and electronics above cabin comfort. I'm okay with that because I want the pack to be protected, and the air coming out of the vent is still colder than the cabin is... Yeah it's not frigid cold, but it will still cool down the cabin, eventually.

This was never an issue last year so something changed.

My vehicle, which has all the OTA updates plus some dealer installed updates (21P22 from earlier this year) seems to be handling the heat much better this summer than it did before those updates, last summer. I have only gotten one or two incidents of "Drive Mode Not Available" so far this summer, where I had probably a dozen or more last summer.

Summer's not over, but so far it seems better. I still work at the same place and park daily in the same spot (full sun, zero shade, no plug).

 

[SnBGC]

I'm in the same boat as you. I'm unaware of any reduction in the ability to idle the car in high heat. I am not worried about it.



True. Even the software/firmware engineers who made the changes might not know all the impacts of their own changes. Systems integration and software engineering are both rather complex at modern day scale. We do the best we can within time/budget restrictions, though.



What I've noticed is that if I park the car outside, like I do at work, and it heats up, then when I go to use the car, the AC vent flow is not as strong or as cold as it would be if I were starting from a garaged/cooler condition.

So for example let's say Friday and Saturday have the same weather but I parked outside in the morning on Friday. On both days, if I leave to go somewhere around 12pm, then it's gonna take a lot longer for the cabin to be comfortable on Friday (no shade) versus Saturday (garaged).

My GUESS based on my observations is that the HVAC is prioritizing battery pack and electronics above cabin comfort. I'm okay with that because I want the pack to be protected, and the air coming out of the vent is still colder than the cabin is... Yeah it's not frigid cold, but it will still cool down the cabin, eventually.



My vehicle, which has all the OTA updates plus some dealer installed updates (21P22 from earlier this year) seems to be handling the heat much better this summer than it did before those updates, last summer. I have only gotten one or two incidents of "Drive Mode Not Available" so far this summer, where I had probably a dozen or more last summer.

Summer's not over, but so far it seems better. I still work at the same place and park daily in the same spot (full sun, zero shade, no plug).

In the Friday example.....the temp inside the cabin is MUCH hotter than your Saturday example. That is why you observe the difference in HVAC performance.

Your driving pattern is nice because you avoid heat soak. That happens when the vehicle makes frequent trips during the hottest parts of the day and the opportunity to plug the car in while parked isn't available. Make a few trips like that back to back within the span of 60-90 min and the cooling system won't be able to cool the battery fast enough once the vehicle is started unless you are moving down the road. Get in the car with a heat soaked battery from a recent drive in very hot ambient temps and then get stuck in crawling traffic will expose the limitations of the cooling system. I have observed that situation about 3 times this year so far. Was never an issue last year.

If you consider how many miles I have on my car and then consider that I don't road trip and my commute to work is average distance then it highlights how often I use the vehicle during the day. I probably get in and out of the car 20-30 times per day. For 9 months out of the year I can start and stop the vehicle each time. During the summer months I really need to consider how long I might be parked and think about leaving the car running to avoid heat soak. Last summer I left the car running quite often and this summer I am doing the opposite just to see what happens. I am starting to see a pattern where leaving the car running might be the better option vs shutting off the car at each stop.

This same thing occurs with ICE vehicles BTW, it is just that most people don't observe it since the recovery time to cool the engine and transmission is very quick once the vehicle is started and the coolant starts circulating. The coolant tube in an EV are much smaller diameter and pressure so it takes a LOT longer to circulate for effective heat transfer.

 

[MightyMike]

When I am parked in 90 degree blacktop and not charging, when I get in, I'll see it about 5-10 degrees higher. After driving for a few minutes and getting some airflow, it goes down, and registers a normal temperature.

If I am plugged in and fast-charging in 90 degree temperature, my departing temperature is extremely high (say in the 110-115 degree range). But then it too drops as I drive. In fact, I go out of my way to drive very softly after fast charging because I don't want to stress the batteries while under high temperature (which I assume is because of the charging).

Mike

 

[Mach1E]

And of course you know the ambient temp is never 145F so that reading on the screen is not coming from that sensor out front.

I agree, that reading on the screen should be ambient but it is not. It is the temp under the hood behind the radiator.

Actually…… if you’re driving on the roads in Phoenix, they can be up to 180 degrees!

https://www.scientificamerican.com/article/to-beat-the-heat-phoenix-paints-its-streets-gray/#

“
Experts say road temperatures in the Phoenix area can rise to 180 degrees on a hot day. That absorbed energy remains in paved surfaces for hours, radiating heat back into nighttime air. Higher overnight temperatures result in warmer mornings, creating a cycle of urban heat island effect.

Researchers found that the greatest temperature differential was near the road surface, with less dramatic results 6 feet above the ground.”

 

[STL-Mach-E]

Experience same thing with mine. At least 10 degrees over reported temps on weather apps after 20 minutes of driving.. Showing 113 this week, when daytime temps topped at about 100.

 

[Mach-Lee]

At any rate, the first time it happened to me this year.....the display was reading around 120F like normal and then I got caught in a traffic jam. I was on an incline in 1PD and watched the temp display count up from 123F to 142F in the span of 60 seconds or so. Then the A/C started blowing warm and I was starting to panic. I turned off 1PD and the temps stabilized and even began falling. It dropped to around 135F or so and then traffic started moving again. Once I got up to 40-45 mph then the temps fell like a rock. All the way down to 112F where it remained for the rest of my 40 min drive.

I don't know what temp the car needs to be plugged in to cool. Seems like anything in the 115F and above displayed on the Sync screen is a good bet the car will start cooling when plugged in. Doesn't happen every time though. So I am not really that certain. ??

Sounds like the airflow reversed when you stopped on the incline and the heat from the A/C condenser started warming up the temp sensor. If you had wind blowing from behind or the radiator fan didn't start up fast enough after slowing down the temp would shoot up rapidly like that.

I'm not sure how old your powertrain software is, but you'll probably notice a difference in behavior after the recall updates. I know they increased the averaging interval on the outdoor temp sensor in recent software.

Temp sensor placement on EV's is hard because of the desire to have a closed front for aero, and wanting to place the temp sensor somewhere where there's good airflow to eliminate radiation forcing while stopped or traveling at low speeds.

I think 45ºC/113ºF is the plug-in warning threshold.

 

[SnBGC]

Sounds like the airflow reversed when you stopped on the incline and the heat from the A/C condenser started warming up the temp sensor. If you had wind blowing from behind or the radiator fan didn't start up fast enough after slowing down the temp would shoot up rapidly like that.

I'm not sure how old your powertrain software is, but you'll probably notice a difference in behavior after the recall updates. I know they increased the averaging interval on the outdoor temp sensor in recent software.

Temp sensor placement on EV's is hard because of the desire to have a closed front for aero, and wanting to place the temp sensor somewhere where there's good airflow to eliminate radiation forcing while stopped or traveling at low speeds.

I think 45ºC/113ºF is the plug-in warning threshold.

I was at the dealership last Friday. They said the HVBJB recall is showing as pending for my car. I received the 2.8.2 and 2.8.3 OTAs about 2 months ago which said BlueCruise was added but it doesn't work. Since then there have been no further OTAs to my car.

 

[SnBGC]

I think I found it.
There is a temp sensor out front in the bumper and several temp sensors under the hood. One of those sensors under the hood is picked up by the APIM as ambient air which is really air intake temp in an ICE. The PCM for an ICE needs to know the under hood temp to calculate air density for fuel trim so the terminology is similar but not exactly the same.

The sensor out front in the bumper is picked up by the SOBDCM C as outdoor air temp. That reads correctly. I measured ambient temp at that sensor with an IR temp and a thermocouple device and it showed 87F, just like the scan tool shows.

Then I measured the various components under the hood and they were all right at 97F, like the Sync screen shows.

At this point I can only suspect a programming error in respect to which sensor is being looked at for the Sync screen reading. When I get time, I will unplug that sensor up front and see if the Sync screen temp display changes at all. I am willing to bet it won't be affected.

 

[Mach-Lee]

I think I found it.
There is a temp sensor out front in the bumper and several temp sensors under the hood. One of those sensors under the hood is picked up by the APIM as ambient air which is really air intake temp in an ICE. The PCM for an ICE needs to know the under hood temp to calculate air density for fuel trim so the terminology is similar but not exactly the same.

The sensor out front in the bumper is picked up by the SOBDCM C as outdoor air temp. That reads correctly. I measured ambient temp at that sensor with an IR temp and a thermocouple device and it showed 87F, just like the scan tool shows.

Then I measured the various components under the hood and they were all right at 97F, like the Sync screen shows.

At this point I can only suspect a programming error in respect to which sensor is being looked at for the Sync screen reading. When I get time, I will unplug that sensor up front and see if the Sync screen temp display changes at all. I am willing to bet it won't be affected.

The bumper sensor is called the ambient air temperature (AAT) sensor and is actually wired directly to the PCM. The PCM reads the value and sends out the reading to all the various modules on the CAN busses. There are no other ambient temp sensors outside the cabin or under the hood. Only coolant temp sensors.

The temp reading parameters will not update when the car is stopped. Basically I did an experiment where I blew a heater on the outdoor temp sensor with the ignition on, and none of the readings changed anywhere. It continued to use the last temp reading from the last time the car was driven, even though everything has fully cooled down (parked for 12+ hours and garage was ~15ºF cooler than last reading). Nothing in the car was as warm as the last reading.

The current software will not update the outdoor temp unless the vehicle starts moving, I think the spec is you have to drive above 20 mph for at least 90 seconds before it will update. Below that speed it probably uses the last value.

I will have to double check the outdoor temp reading in the SOBDMC again, IIRC that didn't change on my car but it seems to on yours. Perhaps that is a difference with the newer software. Yours might not have the averaging algorithm on everything while stopped.

I think the PCM is still sharing the live AAT readings in the background, that's why the SOBDMC was updating even though other indications weren't? It's not because it has it's own sensor. You can try the hairdryer test too while parked to see what changes and what doesn't.

 

[Mach1E]

The bumper sensor is called the ambient air temperature (AAT) sensor and is actually wired directly to the PCM. The PCM reads the value and sends out the reading to all the various modules on the CAN busses. There are no other ambient temp sensors outside the cabin or under the hood. Only coolant temp sensors.

The temp reading parameters will not update when the car is stopped. Basically I did an experiment where I blew a heater on the outdoor temp sensor with the ignition on, and none of the readings changed anywhere. It continued to use the last temp reading from the last time the car was driven, even though everything has fully cooled down (parked for 12+ hours and garage was ~15ºF cooler than last reading). Nothing in the car was as warm as the last reading.

The current software will not update the outdoor temp unless the vehicle starts moving, I think the spec is you have to drive above 20 mph for at least 90 seconds before it will update. Below that speed it probably uses the last value.

I will have to double check the outdoor temp reading in the SOBDMC again, IIRC that didn't change on my car but it seems to on yours. Perhaps that is a difference with the newer software. Yours might not have the averaging algorithm on everything while stopped.

I think the PCM is still sharing the live AAT readings in the background, that's why the SOBDMC was updating even though other indications weren't? It's not because it has it's own sensor. You can try the hairdryer test too while parked to see what changes and what doesn't.

So bottom line? It is reading an accurate temperature.

And apparently the road is hotter than people think.

Go figure, the weather forecast doesn’t account for when it’s “hot enough to fry an egg” on the road.

 

[SnBGC]

The bumper sensor is called the ambient air temperature (AAT) sensor and is actually wired directly to the PCM. The PCM reads the value and sends out the reading to all the various modules on the CAN busses. There are no other ambient temp sensors outside the cabin or under the hood. Only coolant temp sensors.

The temp reading parameters will not update when the car is stopped. Basically I did an experiment where I blew a heater on the outdoor temp sensor with the ignition on, and none of the readings changed anywhere. It continued to use the last temp reading from the last time the car was driven, even though everything has fully cooled down (parked for 12+ hours and garage was ~15ºF cooler than last reading). Nothing in the car was as warm as the last reading.

The current software will not update the outdoor temp unless the vehicle starts moving, I think the spec is you have to drive above 20 mph for at least 90 seconds before it will update. Below that speed it probably uses the last value.

I will have to double check the outdoor temp reading in the SOBDMC again, IIRC that didn't change on my car but it seems to on yours. Perhaps that is a difference with the newer software. Yours might not have the averaging algorithm on everything while stopped.

I think the PCM is still sharing the live AAT readings in the background, that's why the SOBDMC was updating even though other indications weren't? It's not because it has it's own sensor. You can try the hairdryer test too while parked to see what changes and what doesn't.

Now that you mention it.. ..those temp readings were static the entire time I was parked in the driveway. ?

The ambient temp was 88F according to my thermometer on the porch. And the under hood temp was 97F. I measured several components that I was able to reach with the plastic covers removed.

 

[SnBGC]

The bumper sensor is called the ambient air temperature (AAT) sensor and is actually wired directly to the PCM. The PCM reads the value and sends out the reading to all the various modules on the CAN busses. There are no other ambient temp sensors outside the cabin or under the hood. Only coolant temp sensors.

The temp reading parameters will not update when the car is stopped. Basically I did an experiment where I blew a heater on the outdoor temp sensor with the ignition on, and none of the readings changed anywhere. It continued to use the last temp reading from the last time the car was driven, even though everything has fully cooled down (parked for 12+ hours and garage was ~15ºF cooler than last reading). Nothing in the car was as warm as the last reading.

The current software will not update the outdoor temp unless the vehicle starts moving, I think the spec is you have to drive above 20 mph for at least 90 seconds before it will update. Below that speed it probably uses the last value.

I will have to double check the outdoor temp reading in the SOBDMC again, IIRC that didn't change on my car but it seems to on yours. Perhaps that is a difference with the newer software. Yours might not have the averaging algorithm on everything while stopped.

I think the PCM is still sharing the live AAT readings in the background, that's why the SOBDMC was updating even though other indications weren't? It's not because it has it's own sensor. You can try the hairdryer test too while parked to see what changes and what doesn't.

I tried same basic test as you with same conclusion. In my case, I had to drive around for 5 minutes before anything changed. Even the SOBDMC reading remained static while parked. I found this note in the WSM...

The only volt reading I can find was in the PCM, which is always a clue to me that reading comes from an actual sensor vs a calculated value.

The values displayed in the SOBDMC and HVAC module don't have a volt value so those are either calculated or now apparently shared from some other module such as the PCM? That kinda complicates things because I like knowing if I am looking at an actual reading or something from a look up table.

I think I will try one more experiment and report back what I observe.....let's find out if those reading change when stopped but still in D (not in P).

So bottom line? It is reading an accurate temperature.

And apparently the road is hotter than people think.

Go figure, the weather forecast doesn’t account for when it’s “hot enough to fry an egg” on the road.

There is a PID in the HVAC module for "Unfiltered Ambient Air Temp". I looked at that while driving and it was the same as the temp displayed on the screen.

Maybe that temp display on the screen should read "Road Temp". Which would match the speedometer anyway......

 

[cjfarmer]

We've got an MME RWD ER (Infinite Blue) that drives and handles well, but as the temperatures here in Phoenix have started to climb, the outside air temperature shown on the display reads high by 13 to 16 degrees. I assume the car is using the outside air temperature to manage the batteries and the vehicle performance. Has anyone else seen this type of error? Is it harmful to the car (especially the batteries)?

For example here are photos from this afternoon. Weather.com reported the temperature at 113 degrees, while the MME displayed 129 degrees.

Thoughts?

Thanks!

Rick

I was told by phoenix ford dealership, it appears to be a programming issue ford engineer was working on the programming. to fix it . mine was reading 130 when it was 105 outside.

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